1. Field of the Invention
The present invention relates to a new and improved joint assembly and to a method of achieving the novel joint assembly. The joint assembly of the invention may have particular application to pacemakers, and more specifically, for connecting a helically wound lead conductor coil to an electrode.
2. State of the Prior Art
Electrical stimulation of body tissue and organs as a method of treating various pathological conditions is becoming quite commonplace. Such stimulation generally entails making some type of electrical contact with the body tissue or organ. In particular, with respect to the heart, electrical leads have been implanted by a thoracotomy in which an electrode formed on the end of the lead is physically implanted into the myocardial tissues.
Various electrode structures and various techniques for implanting those electrode structures into such body tissue as the heart, or myocardium, have been developed. Typically, electrodes attached to the heart are stimulated by a cardiac pacemaker which may be implanted within the patient's body.
Bipolar systems utilizing coaxial leads have come to be widely used. In coaxial leads, the two conductors are shaped into a small helix surrounded by a larger helix resulting in a much smaller pulse generator connector block. Nonetheless, there is continuing emphasis on developing leads and connectors of ever smaller sizes.
It is mandatory that the outer peripheral surface of the electrode remain unaffected following an operation of joining a lead to the electrode. For this reason, it has been customary to attach the lead, usually helically wound, to a reduced end portion of the electrode by spot or laser welding or, alternatively, by crimping. In either event, a minimum size limit has been effectively reached because of the nature of the design of those constructions.
Accordingly, efforts to achieve an acceptable connection with further miniaturization has required consideration of other concepts. It is in light of the current state of the art as just related that the present invention has been conceived and reduced to practice.